oversized bearing balls for ball nuts

Hello List,
I just received 48" of .750X.200 ballscrew and a couple of nuts from
McMaster-Carr to put into my Mill/Drill. They were advertised as 13/64
pitch but they really are .200 pitch. They are made by Nook industries.
One nut has less than .001 backlash but the other has .006 backlash. I need
to find a source for oversized balls to improve this. I called Nook and
they have oversized balls but they want .20 each for them so I'd have half
the cost of the nut if I guessed right the first time! They said I should
be able to find them over the counter for much less but I haven't had any
luck yet. The installed balls are .141 so I'm guessing I'll need .146 or
.147
to get the backlash down. Any ideas where I might find these?

Thanks!
Joel